CN115335164A - Coated cutting tool and cutting tool - Google Patents

Abstract

The coated tool (1) according to the invention has a base body (10) and a coating (20). The substrate (10) contains a plurality of boron nitride particles. A coating (20) is located on the substrate (10). In addition, when measuring the hardness by pressing the indenter to a depth of 20% of the coating (20) while changing the indentation load of the indenter from the surface of the coating (20), the maximum hardness and the minimum hardness among the hardness The maximum hardness difference of the difference is 4 GPa or more.

Description

Coated and Cutting Tools

technical field

The invention relates to coated tools and cutting tools.

Background technique

As tools used for cutting such as turning and milling, there are known coated tools in which the surface of substrates such as cemented carbide, cermet, and ceramics is coated with a coating film to improve wear resistance and the like (see Patent Document 1). .

prior art literature

patent documents

Patent Document 1: Japanese Patent No. 5160231

Contents of the invention

In the coated tool according to one aspect of the present invention, the coated tool according to the present invention has a substrate and a coating layer. The matrix contains a plurality of boron nitride particles. The coating is on top of the substrate. In addition, when the hardness is measured by pressing the indenter to a depth of 20% of the coating layer while changing the indentation load of the indenter from the surface of the coating, the maximum hardness difference is the difference between the maximum hardness and the minimum hardness among the hardnesses. It is above 4GPa.

Description of drawings

FIG. 1 is a perspective view showing an example of a coated tool according to the embodiment.

Fig. 2 is a side sectional view showing an example of a coated tool according to the embodiment.

Fig. 3 is a cross-sectional view showing an example of a coating layer according to the embodiment.

FIG. 4 is a schematic enlarged view of an H portion shown in FIG. 3 .

Fig. 5 is a front view showing an example of the cutting tool according to the embodiment.

Fig. 6 is a table showing the configuration of each sample.

7 is a table showing the results of indentation hardness tests for cBN without a metal layer and cBN with a metal layer.

FIG. 8 is a graph showing the results of an indentation hardness test with respect to cBN without a metal layer and cBN with a metal layer.

FIG. 9 is a graph showing changes in the residual stress of the coating layer when the film thickness of the metal layer is changed.

10 is a table showing the results of a scratch test and a peeling test with respect to cBN without a metal layer and cBN with a metal layer.

Detailed ways

Hereinafter, modes (hereinafter referred to as "embodiments") for implementing the coated tool and the cutting tool of the present invention will be described in detail with reference to the drawings. In addition, the coated tool and cutting tool of this invention are not limited to this embodiment. In addition, each embodiment can be combined suitably within the range that processing content does not conflict. In addition, in each of the following embodiments, the same reference numerals are attached to the same parts, and overlapping descriptions are omitted.

In addition, in the embodiments shown below, expressions such as "constant", "orthogonal", "perpendicular", or "parallel" may be used, but these expressions do not need to be "constant" in the strict sense, Orthogonal, Perpendicular, or Parallel. That is, the above-mentioned respective expressions allow variations in, for example, manufacturing accuracy, installation accuracy, and the like.

In the prior art described above, there is room for further improvement in terms of improving the adhesion between the coating and the substrate.

The present invention is made in view of the above circumstances, and provides a coated tool and a cutting tool capable of improving the bonding between a coating and a substrate.

＜Coated tools＞

FIG. 1 is a perspective view showing an example of a coated tool according to the embodiment. In addition, as shown in FIG. 1 , a coated cutter 1 according to the embodiment has an insert body 2 and a cutting edge portion 3 . In the embodiment, the coated tool 1 is, for example, a parallelogram-shaped hexahedron having an upper surface and a lower surface (surface intersecting the Z-axis shown in FIG. 1 ).

(blade body 2)

The insert body 2 is formed of, for example, cemented carbide. Cemented carbide contains W (tungsten), specifically WC (tungsten carbide). In addition, the cemented carbide may contain Ni (nickel) and Co (cobalt). In addition, the blade body 2 may also be formed of cermet. The cermet contains, for example, Ti (titanium), specifically TiC (titanium carbide) or TiN (titanium nitride). In addition, the cermet may contain Ni or Co.

At the corner portion of the insert body 2, a support surface 4 for mounting the cutting edge portion 3 is provided. In addition, a through-hole 5 that penetrates the blade body 2 up and down is provided at a central portion of the blade body 2 . Bolts 75 (see FIG. 5 ) for attaching the coated tool 1 to a shank 70 described later are inserted into the through holes 5 .

(cutting edge 3)

The cutting edge portion 3 is integrated with the blade body 2 by being attached to the support surface 4 of the blade body 2 .

The cutting edge portion 3 has a first surface 6 (here, an upper surface) and a second surface 7 (here, a side surface) continuous with the first surface 6 . In the embodiment, the first surface 6 functions as a "rake face" that scrapes off chips generated by cutting, and the second face 7 functions as a "flank face". The cutting edge 8 is located at least a part of the ridgeline where the first surface 6 and the second surface 7 intersect, and the coated tool 1 cuts the workpiece by contacting the workpiece with the cutting edge 8 .

Referring to FIG. 2 , the structure of the cutting edge portion 3 will be described. Fig. 2 is a side sectional view showing an example of a coated tool according to the embodiment. As shown in FIG. 2 , the cutting edge portion 3 has a substrate 10 and a coating layer 20 .

(substrate 10)

The substrate 10 contains a plurality of boron nitride particles. In the embodiment, the substrate 10 is a cubic boron nitride (cBN) sintered body, and contains a plurality of cubic boron nitride particles. In addition, in the embodiment, the substrate 10 may include a binder phase containing TiN, Al, Al ₂ O ₃ or the like between a plurality of boron nitride particles. A plurality of boron nitride particles are firmly bound by such a binder phase. Also, the substrate 10 does not necessarily have to have a binder phase.

On the lower surface of the base body 10, a substrate 30 formed of, for example, cemented carbide or cermet may also be provided. In this case, the base body 10 is bonded to the support surface 4 of the insert body 2 via the substrate 30 and the bonding material 40 . The bonding material 40 is, for example, brazing filler metal. In parts other than the support surface 4 of the blade body 2 , the base body 10 may be bonded to the blade body 2 via a bonding material 40 .

(coating 20)

The coating layer 20 is coated on the base body 10 for the purpose of improving the wear resistance and heat resistance of the cutting edge portion 3 , for example. In the example of FIG. 2 , the coating 20 covers the blade body 2 and the cutting edge portion 3 integrally. It is sufficient that the coating 20 is at least located on the substrate 10 . When the coating layer 20 is located on the upper surface of the base 10 corresponding to the first surface 6 of the cutting edge portion 3, the wear resistance and heat resistance of the first surface 6 are high. When the coating layer 20 is located on the side of the base 10 corresponding to the second surface 7 of the cutting edge portion 3, the second surface 7 has high wear resistance and heat resistance.

Here, referring to FIG. 3 , a specific configuration of the coating layer 20 will be described. FIG. 3 is a cross-sectional view showing an example of the coating layer 20 according to the embodiment.

As shown in FIG. 3 , the coating 20 has a hard layer 21 . The hard layer 21 is a layer more excellent in wear resistance than the metal layer 22 described later. The hard layer 21 has one or more metal nitride layers. The hard layer 21 may also be one layer. In addition, as shown in FIG. 3, a plurality of metal nitride layers may overlap. In addition, the hard layer 21 may have a laminated portion 23 in which a plurality of metal nitride layers are laminated, and a third metal nitride layer 24 located on the laminated portion 23 . The configuration of this hard layer 21 will be described later.

(metal layer 22)

In addition, the coating 20 has a metal layer 22 . The metal layer 22 is located between the substrate 10 and the hard layer 21 . Specifically, the metal layer 22 is in contact with the upper surface of the substrate 10 on one side (here, the lower surface), and is in contact with the lower surface of the hard layer 21 on the other side (here, the upper surface). catch.

The bonding property of the metal layer 22 and the substrate 10 is higher than that of the hard layer 21 . Examples of metal elements having such properties include Zr, V, Cr, W, Al, Si, and Y. The metal layer 22 contains at least one or more metal elements among the above-mentioned metal elements.

In addition, simple substances of Ti, Zr, V, Cr, and Al are not used as the metal layer 22 . This is because they have a low melting point and low oxidation resistance, so they are not suitable for cutting tools. In addition, the simple substance of Hf, the simple substance of Nb, the simple substance of Ta, and the simple substance of Mo have low bonding properties with the substrate 10 . However, there is no such limitation in alloys containing Ti, Zr, V, Cr, Ta, Nb, Hf, and Al.

The metal layer 22 may be an Al—Cr alloy layer containing an Al—Cr alloy. Since such a metal layer 22 has a particularly high bonding property with the substrate 10 , the effect of improving the bonding property between the substrate 10 and the coating layer 20 is high.

When the metal layer 22 is an Al—Cr alloy layer, the Al content in the metal layer 22 may be greater than the Cr content in the metal layer 22 . For example, the composition ratio (atomic %) of Al and Cr in the metal layer 22 may be 70:30. By setting such a composition ratio, the bonding property of the base body 10 and the metal layer 22 becomes higher.

The metal layer 22 may contain components other than the aforementioned metal elements (Zr, V, Cr, W, Al, Si, Y). However, from the viewpoint of bonding with the substrate 10, the metal layer 22 may contain at least 95 atomic % or more of the above-mentioned metal elements in total. More preferably, the metal layer 22 contains the above-mentioned metal elements in a total amount of 98 atomic % or more. For example, when the metal layer 22 is an Al—Cr alloy layer, the metal layer 22 may contain at least 95 atomic % or more of Al and Cr in total. In addition, the metal layer 22 may contain at least Al and Cr in a total amount of 98 atomic % or more. In addition, the ratio of the metal component in the metal layer 22 can be specified, for example, by analysis using EDS (Energy Dispersive Spectroscopy).

In addition, since Ti has poor wettability with the base 10 in the embodiment, it is preferable that the metal layer 22 does not contain Ti as much as possible from the viewpoint of improving the bondability with the base 10 . Specifically, the content of Ti in the metal layer 22 is preferably 15 atomic % or less.

In this way, in the coated cutting tool 1 of the embodiment, by providing the metal layer 22 having higher wettability with the base 10 than the hard layer 21 between the base 10 and the hard layer 21, the contact between the base 10 and the coating can be improved. 20 associativity. In addition, since the metal layer 22 is also highly bonded to the hard layer 21 , it is also difficult for the hard layer 21 to peel off from the metal layer 22 .

In addition, cBN used as the base 10 is an insulator, and cBN as an insulator has room for improvement in terms of adhesion to a film formed by PVD (Physical Vapor Deposition). On the other hand, in the coated tool 1 according to the embodiment, since the conductive metal layer 22 is provided on the surface of the base 10 , the hard layer 21 formed by PVD has a high bonding property with the metal layer 22 .

(hard layer 21)

Next, the configuration of the hard layer 21 will be described with reference to FIG. 4 . FIG. 4 is a schematic enlarged view of an H portion shown in FIG. 3 .

As shown in FIG. 4 , the hard layer 21 has a laminated portion 23 located on the metal layer 22 and a third metal nitride layer 24 located on the laminated portion 23 .

The laminated portion 23 has a plurality of first metal nitride layers 23a and a plurality of second metal nitride layers 23b. The laminated portion 23 has a structure in which first metal nitride layers 23 a and second metal nitride layers 23 b are alternately laminated.

The thicknesses of the first metal nitride layer 23 a and the second metal nitride layer 23 b are each 50 nm or less. Thus, by forming the first metal nitride layer 23a and the second metal nitride layer 23b thin, the residual stress of the first metal nitride layer 23a and the second metal nitride layer 23b is small. Thereby, for example, peeling and cracking of the first metal nitride layer 23a and the second metal nitride layer 23b are less likely to occur, so the durability of the coating layer 20 is high.

The first metal nitride layer 23a is a layer in contact with the metal layer 22, and the second metal nitride layer 23b is formed on the first metal nitride layer 23a.

The first metal nitride layer 23 a and the second metal nitride layer 23 b may contain the metal contained in the metal layer 22 .

For example, two kinds of metals (here, "first metal" and "second metal") are contained in the metal layer 22 . In this case, the first metal nitride layer 23a contains nitrides of the first metal and the third metal. The third metal is a metal not included in the metal layer 22 . In addition, the second metal nitride layer 23b contains nitrides of the first metal and the second metal.

For example, in an embodiment, metal layer 22 may contain Al and Cr. In this case, the first metal nitride layer 23a may contain Al. Specifically, the first metal nitride layer 23a may be an AlTiN layer containing AlTiN which is a nitride of Al and Ti. In addition, the second metal nitride layer 23b may be an AlCrN layer containing AlCrN which is a nitride of Al and Cr.

Thus, by making the 1st metal nitride layer 23a containing the metal contained in the metal layer 22 be located on the metal layer 22, the bonding property of the metal layer 22 and the hard layer 21 is high. Thereby, since the hard layer 21 is hard to peel off from the metal layer 22, the durability of the coating layer 20 is high.

The AlTiN layer that is the first metal nitride layer 23a is excellent in, for example, wear resistance in addition to the bonding property with the metal layer 22 described above. In addition, the AlCrN layer that is the second metal nitride layer 23b is excellent in heat resistance and oxidation resistance, for example. In this way, the coating layer 20 can control the properties such as wear resistance and heat resistance of the hard layer 21 by including the first metal nitride layer 23a and the second metal nitride layer 23b having different compositions. Thereby, the tool life of the coated tool 1 can be extended. For example, in the hard layer 21 of the embodiment, while maintaining the heat resistance possessed by AlCrN, mechanical properties such as bonding with the metal layer 22 and wear resistance can be improved.

In addition, the laminated part 23 can also be formed into a film by the arc ion plating method (AIP method), for example. The AIP method is a method of forming a metal nitride film (here, AlTiN and AlCrN) by evaporating a target metal (here, an AlTi target and an AlCr target) and bonding _N2 by arc discharge in a vacuum atmosphere. In addition, the metal layer 22 can also be formed into a film by the AIP method.

The third metal nitride layer 24 may be located on the laminated portion 23 . Specifically, the third metal nitride layer 24 is in contact with the second metal nitride layer 23 b in the laminated portion 23 . The third metal nitride layer 24 is, for example, a metal nitride layer (AlTiN layer) containing Ti and Al, like the first metal nitride layer 23a.

The thickness of the third metal nitride layer 24 may be thicker than the respective thicknesses of the first metal nitride layer 23a and the second metal nitride layer 23b. Specifically, when the thickness of the first metal nitride layer 23 a and the second metal nitride layer 23 b is 50 nm or less, the thickness of the third metal nitride layer 24 may be 1 μm or more. For example, the thickness of the third metal nitride layer 24 may be 1.2 μm.

Thus, for example, when the coefficient of friction of the third metal nitride layer 24 is low, the anti-seizing property of the coated tool 1 can be improved. In addition, for example, when the hardness of the third metal nitride layer 24 is high, the wear resistance of the coated tool 1 can be improved. In addition, for example, when the oxidation initiation temperature of the third metal nitride layer 24 is high, the oxidation resistance of the coated tool 1 can be improved.

In addition, the thickness of the third metal nitride layer 24 may be thicker than the thickness of the laminated portion 23 . Specifically, in the embodiment, when the thickness of the laminated portion 23 is 0.5 μm or less, the thickness of the third metal nitride layer 24 may be 1 μm or more. For example, when the thickness of the laminated portion 23 is 0.3 μm, the thickness of the third metal nitride layer 24 may be 1.2 μm. In this way, by making the third metal nitride layer 24 thicker than the laminated portion 23 , the effect of improving the above-mentioned blocking resistance, wear resistance, and the like is higher.

In addition, the thickness of the metal layer 22 may be, for example, not less than 0.1 μm and less than 0.6 μm. That is, the metal layer 22 may be thicker than each of the first metal nitride layer 23 a and the second metal nitride layer 23 b, and may be thinner than the laminated portion 23 .

＜Cutting tools＞

Next, referring to FIG. 5 , the configuration of a cutting tool including the above-mentioned coated tool 1 will be described. Fig. 5 is a front view showing an example of the cutting tool according to the embodiment.

As shown in FIG. 5 , the cutting tool 100 of the embodiment has a coated tool 1 and a holder 70 for fixing the coated tool 1 .

The handle 70 is a rod-shaped member extending from a first end (upper end in FIG. 5 ) toward a second end (lower end in FIG. 5 ). The handle 70 is made of steel or cast iron, for example. Among these members, it is particularly preferable to use high toughness steel.

The handle 70 has an engaging groove 73 at the end on the first end side. The retaining groove 73 is a portion where the coated cutter 1 is mounted, and has a support surface intersecting the rotational direction of the workpiece, and a limiting side surface inclined relative to the support surface. Screw holes for tightening bolts 75 to be described later are provided on the support surface.

The coating cutter 1 is located in the slot 73 of the handle 70 and is mounted on the handle 70 by a bolt 75 . That is, a bolt 75 is inserted into the through hole 5 of the coated cutter 1 , the tip of the bolt 75 is inserted into a bolt hole formed on the supporting surface of the engaging groove 73 , and the threaded portions are tightened. Thus, the coated cutter 1 is attached to the handle 70 such that the cutting edge 8 (see FIG. 1 ) protrudes outward from the handle 70 .

In the embodiment, a cutting tool used for so-called turning processing is exemplified. As turning processing, for example, inner diameter processing, outer diameter processing, and grooving processing can be cited. In addition, as a cutting tool, it is not limited to use in turning processing. For example, the coated tool 1 can also be used as a cutting tool for milling.

For example, the cutting process of the workpiece includes: (1) the process of rotating the workpiece; (2) the process of cutting the workpiece by bringing the cutting edge 8 of the coated tool 1 into contact with the rotating workpiece; and (3) a step of separating the coated tool 1 from the workpiece. In addition, typical examples of the material of the workpiece include carbon steel, alloy steel, stainless steel, cast iron, and nonferrous metals.

(Example 1: Indentation hardness test)

The inventors of the present application conducted an indentation hardness test on a sample having a coating layer formed on a substrate containing boron nitride particles. The matrix is formed of a plurality of cubic boron nitride particles and a TiN-containing binder phase. The matrix contains about 25% by volume of the binder phase.

The samples were the following two types.

(1) A sample in which a coating layer having a metal layer is formed on cBN (hereinafter referred to as "cBN with a metal layer")

(2) A sample in which a coating layer without a metal layer is formed on cBN (hereinafter referred to as "cBN without a metal layer")

The specific configuration of each sample will be described with reference to FIG. 6 . Fig. 6 is a table showing the configuration of each sample.

As shown in FIG. 6, there is a metal layer cBN, and on a substrate formed of cBN, there is a coating layer formed of a metal layer and a hard layer. Specifically, a metal layer is set on the substrate, and a hard layer is set on the metal layer. On the other hand, cBN without a metal layer has a coating layer formed of a hard layer on a substrate formed of cBN.

There is a metal layer of metal layer cBN containing Al and Cr. A specific composition of such a metal layer is Al ₇₀ Cr ₃₀ . That is, the metal layer contains 70 atomic % of Al and 30 atomic % of Cr. In addition, the thickness of the metal layer was 0.2 μm.

The hard layer with metal layer cBN and without metal layer cBN has a first metal nitride layer, a second metal nitride layer and a third metal nitride layer. The first metal nitride layers and the second metal nitride layers are alternately stacked. In addition, the third metal nitride layer is located on the alternately stacked first metal nitride layer and second metal nitride layer.

In FIG. 6, the ratio of only the metal component of the first metal nitride layer described as TiAlNbWSiN is 42 atomic % for Ti, 48 atomic % for Al, 3 atomic % for Nb, 4 atomic % for W, and 3 atomic % for Si. %. In addition, the first metal nitride layer contains about 100 atomic % of N with respect to 100 atomic % of the metal component. The thickness of one first metal nitride layer is 50 nm.

In the ratio of only the metal component of the second metal nitride layer described as AlCrN in FIG. 6, Al is 70 atomic % and Cr is 30 atomic %. In addition, the second metal nitride layer contains about 100 atomic % of N with respect to 100 atomic % of the metal component. One second metal nitride layer has a thickness of 50 nm.

The total thickness of the plurality of first metal nitride layers and the plurality of second metal nitride layers was 0.5 μm.

The composition of the third metal nitride layer is the same as that of the first metal nitride layer. The thickness of the third metal nitride layer was 2 μm.

The results of the indentation hardness test for this sample are shown in FIGS. 7 and 8 . FIG. 7 is a table showing the results of indentation hardness tests for cBN without a metal layer and cBN with a metal layer, and FIG. 8 is a graph showing the results of the same test.

In addition, this test was performed using the micro-indentation hardness tester "ENT-1100b/a" (made by Elionix Corporation).

Before measuring the hardness, the thickness of the coating is measured in a section of the substrate normal to the surface of the substrate. The thickness of the coating with the metal layer is 2.7 μm. Without the metal layer, the thickness of the coating is 2.5 μm. From the surface of the coating, press the indenter into an amount of 20% of the thickness of the coating. The pressure of the indenter to the coating surface increases approximately by 0.02 μm each time. This pressing depth can be increased by increasing the pressing load. In other words, increasing the indentation depth by 0.02 μm is equivalent to increasing the indentation load approximately by 5 mN.

In this test, if the indenter is pressed to a depth of 20% of the thickness of the coating, the hardness near the surface of the substrate can basically be measured from the surface of the coating. In the present invention, the hardness of the coating is, as described above, the hardness obtained by pressing the indenter to a depth of 20% of the coating while changing the indentation load of the indenter from the surface of the coating. In the indentation hardness test, the deeper the indentation depth, the deeper the hardness can be measured from the coating surface.

In FIG. 8 , the measurement results of cBN with a metal layer are indicated by blank circles, and the measurement results of cBN without a metal layer are indicated by black triangles. As shown in FIG. 8 , it can be seen that cBN with a metal layer has a higher overall hardness than cBN without a metal layer. This increase in hardness is notable in the region with an indentation depth of 300 nm or less. The hardness at an indentation depth of 300 nm or less indicates the hardness of the hard layer. From this, it can be seen that the hardness of the hard layer is higher in the cBN with the metal layer than in the cBN without the metal layer.

This point will be described with reference to FIG. 9 . FIG. 9 is a graph showing changes in the residual stress of the coating layer when the film thickness of the metal layer is changed.

FIG. 9 shows the results of measuring the residual stress of the coating based on the amount of warpage of the stainless steel plate on which the coating with the metal layer was formed. In FIG. 7 , the result for a film thickness of 0 μm represents the residual stress of a coating without a metal layer, that is, a coating with only a hard layer. In addition, the results of film thicknesses of 0.2 μm, 0.4 μm, and 0.6 μm represent the residual stress of the coating layer with the metal layer.

As shown in FIG. 9 , it can be seen that the coating with the metal layer has higher residual stress than the coating without the metal layer. The higher the residual stress, the higher the hardness of the coating. Therefore, it can be seen that the hardness of the coating layer is improved by forming the metal layer.

One of the reasons why the residual stress of the coating layer increases due to the metal layer is considered to be, for example, the following. That is, in PVD coating, a bias voltage is applied to the object to be filmed (cBN, cemented carbide, etc.) to form a metal layer, and more ions are attracted to the object to be filmed when the bias is applied. As a result, it is considered that a large residual stress occurs in the coating with the metal layer compared with the coating without the metal layer.

Also, when the film thickness of the metal layer was set to 0.6 μm, peeling of the coating occurred and residual stress decreased. From these results, the film thickness of the metal layer is preferably not less than 0.1 μm and less than 0.6 μm.

In addition, as shown in FIG. 8 , there is a valley of hardness in the vicinity of the indentation depth of 300 nm in the metal layer cBN. This is a feature not seen in metal-free cBN. As described above, the hardness around the indentation depth of 300 nm indicates the hardness of the metal layer, and since the metal layer is softer than the hard layer, it is considered that such hardness valleys can be formed.

In the measurement results shown in FIG. 6 , the difference between the maximum hardness and the minimum hardness (hereinafter, described as "maximum hardness difference") of cBN without metal layer is less than 4 GPa, while the maximum hardness difference of cBN with metal layer is Above 4GPa. Specifically, the maximum hardness difference of cBN with a metal layer is 8 GPa or more.

Thus, in a coated tool having a maximum hardness difference of 4 GPa or more, there are parts with high hardness and parts with low hardness, and the difference is 4 GPa or more. First, in the case of such a configuration, a case where the portion with low hardness is located farther from the base than the portion with high hardness will be described. For example, when a large impact is applied to the coated tool repeatedly in intermittent machining, since the part with low hardness is located closer to the surface of the coated tool than the part with high hardness, this part is easy to absorb the impact and is not easy to Crash occurs.

Next, a case will be described where the portion with high hardness is located farther from the base than the portion with low hardness. In this case, it is for continuous processing. That is, the portion with high hardness is located closer to the surface of the coated tool, so it is excellent in wear resistance, and the portion with low hardness is absorbed, so it is excellent in wear resistance and impact resistance.

In addition, the metallic layer cBN has the maximum hardness on the surface layer side of the coating. Specifically, the indentation depth of the maximum hardness is smaller than the indentation depth of the minimum hardness.

In this way, the metal-containing layer cBN has the maximum hardness on the surface layer side. In other words, by providing the metal layer, the hardness on the surface layer side of the coating layer can be increased. Therefore, the life as a coated tool can be extended.

Among the results shown in Figure 7, the so-called "maximum hardness" is the maximum value of the hardness in the measurement range (from the surface of the coating to 20% of the depth of the coating), and the so-called "minimum hardness" is the above-mentioned The minimum value of the hardness in the measurement range. The "maximum hardness load" is the indentation load of the indenter with the maximum hardness, and the "maximum hardness depth" is the indentation depth of the indenter with the maximum hardness. The "minimum hardness load" is the indentation load of the indenter with the minimum hardness, and the "minimum hardness depth" is the indentation depth of the indenter with the minimum hardness.

The so-called "maximum hardness difference" is the difference between the maximum hardness and the minimum hardness. The "average hardness" is the average value of the hardness in the measurement range.

The difference between the maximum hardness depth and the minimum hardness depth of cBN with metal layer, that is, the maximum hardness depth difference may be 180 nm or more and 500 nm or less.

The so-called maximum hardness depth difference is 180nm or more, in other words, the change in hardness is relatively moderate, and it can be said that the characteristics of the coated tool are difficult to change drastically. In such a case, breakage is less likely to occur. In addition, the maximum hardness depth difference of 500 nm or less means that the position showing the maximum hardness is relatively close to the position showing the minimum hardness. Therefore, the effect is more remarkable when the maximum hardness difference is 4 GPa or more.

The maximum hardness depth of the metallic layer cBN is not less than 80 nm and not more than 200 nm. If it has such a structure, it will be excellent in abrasion resistance.

The minimum hardness depth of cBN with metal layer is above 300nm. With such a structure, breakage is less likely to occur even during intermittent processing.

When the average value of the hardness of cBN with metal layer is taken as the average hardness, the difference between the average hardness and the maximum hardness is 3.0 GPa or less. When it has such a structure, in other words, since it is a coating layer with relatively high hardness as a whole, it is excellent in abrasion resistance.

In cBN with a metal layer, the difference between the average hardness and the minimum hardness is 2.0 GPa or more. In other words, when it has such a structure, since it becomes a coating layer with relatively high hardness as a whole, it is excellent in abrasion resistance.

The maximum hardness is above 25GPa. If it has high hardness like this, it will be excellent in abrasion resistance.

(Example 2: scratch test and peel test)

In addition, the inventors of the present application conducted a scratch test and a peeling test on the samples of the cBN without the metal layer and the cBN with the metal layer. The scratch test is evaluated by the magnitude of the peeling load, and the larger the peeling load, the more difficult it is to peel. In addition, the longer the peeling time, the more difficult it is to peel.

The scratch test was carried out under the conditions of a diamond indenter with a tip shape having an R (radius of curvature) of 200 μm at a speed of 10 mm/min and a load speed of 100 N per minute.

Peeling test, for the quenched material of the processed material SCM415, using the sample of the tool shape of CNGA120408S01225, under the processing conditions of cutting speed: 150m/min, cutting speed: 0.1mm/turn, depth of cut: 0.2mm, the evaluation is up to Time for the hard layer to peel off.

The peel load and peel time are shown in FIG. 10 . FIG. 10 is a table showing the results of a scratch test and a peel test for cBN without a metal layer and cBN with a metal layer. As shown in FIG. 8 , in cBN with a metal layer, the peeling load was larger than that in cBN without a metal layer, and the peeling time was also significantly longer. In addition, in Fig. 10, "80>" indicates that the peeling load is lower than 80N but close to 80N (at least 75N or more). Similarly, in FIG. 10, "40>" indicates that the peeling time is less than 40 minutes but close to 40 minutes (at least 35 minutes or more). In this way, cBN with a metal layer is less prone to peeling of the coating than cBN without a metal layer, that is, the durability of the coating is high.

＜Modifications＞

In the above-described embodiment, the coated tool 1 is coated with the coating layer 20 by mounting the substrate 10 formed of boron nitride particles or the like on the insert body 2 formed of cemented carbide or the like. explained. Not limited thereto, the coated cutting tool of the present invention, for example, also can be that the shape of upper surface and lower surface is the hexahedron shape substrate of parallelogram all is cubic boron nitride quality sintered body, is formed with coating layer on such substrate of knives.

In the above embodiment, an example was shown in which the upper and lower surfaces of the coated cutter 1 are parallelograms, but the upper and lower surfaces of the coated cutter 1 may also have a rhombus, a square, or the like. In addition, the shapes of the upper surface and the lower surface of the coated cutter 1 may also be triangular, pentagonal, hexagonal, etc.

In addition, the shape of the coated cutter 1 may be positive or negative. The positive type is a type in which the sides are inclined with respect to a central axis passing through the center of the upper surface and the center of the lower surface of the coated tool 1 , and the negative type is a type in which the sides are parallel to the above-mentioned central axis.

In the above-mentioned embodiment, an example in which the substrate 10 contains cubic boron nitride (cBN) particles has been described. Not limited thereto, the substrate disclosed in the present application may also contain, for example, particles of hexagonal boron nitride (hBN), rhombohedral boron nitride (rBN), wurtzite boron nitride (wBN), or the like.

In the above-mentioned embodiment, it was described that the coated tool 1 is used for cutting, but the coated tool of the present application can also be applied to tools other than cutting tools such as digging tools and bladed objects.

More effects and modifications can be easily derived by those skilled in the art. Therefore, broader aspects of the present invention are not limited to the specific details and representative embodiments that have been described and described above. Accordingly, various changes may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

Symbol Description

1 Coated tool

2 Blade body

3 cutting edge

4 bearing surface

5 through holes

6 Side 1

7 Side 2

8 cutting edges

10 substrate

20 coats

21 hard layer

22 metal layers

23 Lamination section

23a First metal nitride layer

23b Second metal nitride layer

24 3rd metal nitride layer

30 substrates

40 joint material

70 handle

73 card slot

75 bolts

100 cutting tools

Claims (20)

1. A coated tool having: a substrate comprising a plurality of boron nitride particles, and a coating on said substrate, When measuring the hardness by pressing the indenter to a depth of 20% of the coating layer while changing the indentation load of the indenter from the surface of the coating layer, the maximum hardness and the minimum hardness among the hardness The maximum hardness difference of the difference is 4 GPa or more. 2. The coated cutting tool according to claim 1, wherein the maximum hardness difference is 8 GPa or more. 3. A coated tool according to claim 1 or 2, wherein, Assuming that the depth of the maximum hardness is the maximum hardness depth, and when the depth of the minimum hardness is the minimum hardness depth, the maximum hardness depth is shallower than the minimum hardness depth. 4. The coated cutting tool according to claim 3, wherein the difference between the maximum hardness depth and the minimum hardness depth is 180 nm or more and 500 nm or less. 5. The coated cutting tool according to claim 3 or 4, wherein the maximum hardness depth is 80 nm or more and 200 nm or less. 6. The coated cutting tool according to any one of claims 3 to 5, wherein the minimum hardness depth is 300 nm or more. 7. The coated cutting tool according to any one of claims 1 to 6, wherein the hardness has an average hardness, and the difference between the average hardness and the maximum hardness is 3.0 GPa or less. 8. The coated cutting tool according to any one of claims 1 to 7, wherein the hardness has an average hardness, and the difference between the average hardness and the minimum hardness is 2.0 GPa or more. 9. The coated cutting tool according to any one of claims 1 to 8, wherein the maximum hardness is 25 GPa or more. 10. A coated tool according to any one of claims 1 to 9, wherein the coating comprises: Hard layer; A metal layer other than simple substances of Ti, Zr, V, Cr, Ta, Nb, Hf, and Al located between the substrate and the hard layer. 11. The coated cutting tool according to claim 10, wherein the metal layer contains at least one element among Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Si, and Y. 12. The coated cutting tool according to claim 11, wherein the metal layer contains 95 atomic % or more of the element. 13. The coated cutting tool according to any one of claims 10 to 12, wherein the metal layer contains Al and Cr in a total amount of 95 atomic % or more. 14. The coated cutting tool according to any one of claims 10 to 13, wherein the Ti content in the metal layer is 15 atomic % or less. 15. A coated tool according to any one of claims 10 to 14, wherein the matrix has a binder phase between the boron nitride particles. 16. The coated cutting tool according to any one of claims 10 to 15, wherein the hard layer has one or more metal nitride layers. 17. The coated cutting tool according to claim 16, wherein the metal nitride layer in contact with the metal layer contains the metal contained in the metal layer. 18. A coated tool according to claim 16 or 17, wherein the metal nitride layer comprises: a first metal nitride layer; A second metal nitride layer having a composition different from that of the first metal nitride layer. 19. The coated tool according to any one of claims 1 to 18, having a support formed of cemented carbide or cermet, The base body is located on the support body. 20. A cutting tool comprising: Rod-shaped handle with a slot at the end; The coated cutting tool according to any one of claims 1-19 located in the slot.

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